1. Field of the Invention
The present invention relates to a method for manufacturing a foil-like electrical connector for solar cells in order to connect the solar cells to form modules, the connector having a conductive layer and at least one insulating surface layer, and the present invention further relates to a foil-like electrical connector manufactured according to such a method, and a method for electrically connecting at least two solar cells to form a solar module, with the aid of a connector.
2. Description of Related Art
Interdigitated back-contact (IBC) cells, whose backside metal-plated structure is composed of two intermeshing metal finger combs, are part of the related art. Two such adjacent cells of a string are connected by soldering multiple small connecting tabs or a fairly large rectangular or bone-shaped copper sheet onto the edge pads which are part of the two cells to be connected, in each case at different polarities. The related art in this regard is characterized by published international patent application document WO 2005/013322 or published U.S. patent application document US 2005/0268959 A1.
Furthermore, for MWT cells it has been proposed to use backside connectors which have the form of an interdigital structure, i.e., intermeshing combs having wide copper sheets. This structure is designed to be present on a so-called backsheet, and in particular, provided on a large-surface plastic film. In this regard, reference is made to U.S. Pat. No. 3,903,428 and U.S. Pat. No. 3,903,427.
The solar cells are then positioned in a matrix array on the produced large-surface backsheets according to the pick-and-place process, and are subsequently connected to the copper sheets, using conductive adhesives.
Published German patent document DE 11 2005 001 252 T2 discloses a connection of solar cells to form a solar cell module, the solar cells being designed as backside-contact cells. A solar cell module includes a plurality of solar cells which are connected to one another as a solar cell matrix. A special connection system electrically contacts the back sides of two adjacent solar cells. The previously known connection system may have a connection which connects a contact point on a back side of one solar cell to a contact point on a back side of another solar cell, in addition a so-called connection shield being present between the solar cells and the connection. The connection shield advantageously provides electrical insulation between the connection and the edges of the solar cells in areas other than the soldering contact points, thus preventing electrical paths in the cells which reduce the efficiency. Specifically, the connection shield prevents soldering agent from migrating to the front sides of the solar cells during the soldering. In addition, the connection shield acts as a cell-to-cell spacer for assembly symmetry. In one embodiment, the connection shield is a one-sided or two-sided band with or without an integral coating. Thus, in the exemplary embodiment according to published German patent document DE 11 2005 001 252 T2 it is described that the connection shield is a polyester band approximately 6.2 mm wide which includes an acrylic-based adhesive.
The known backsheet technical approaches have the disadvantage that the entire back side of the module is usually made of a single flat film material, the film material supporting a structured copper coating. Coating a monolithic piece of film, having the typical dimensions of a cell module of approximately 160 cm×100 cm, with copper and structuring this coating is very problematic. A solder stop layer must be applied to either the copper sheet or the cells to be able to avoid electrical short circuits, which likewise entails technical problems.
As described, the connections of the cells to the backsheet to form a module are established with the aid of conductive adhesives whose resistivity in principle does not reach the low values of solders.